The overall objectives of this project are to study solvent accessibility in the dynamic structure of folded proteins, with particular emphasis on solvent accessibility in the contact region of specifically associating proteins. The associating protein systems being studied are the soybean trypsin inhibitor (STI)-trypsin complex, and the ribosomal proteins L7/L12. The solvent accessibility of backbone NH protons in the folded structure of proteins provides important descriptive information about the dynamics of the proteins conformation in solution, and about the solvent contribution to protein stabilization. Protein-protein interactions of specifically associating proteins underlie many of the mechanisms of cellular regulation and control processes. Characterization of the conformation and the binding of ribosomal proteins L7 and L12 with themselves and with other molecules implicated in functional assays will be a significant contribution to the understanding of ribosomal function in protein synthesis.